Objective: To examine the association between the presence of medically complex comorbidities and the receipt of high-quality preventive care in persons with diabetes. Background: For persons with diabetes, high-quality care includes receipt of preventive services. Researchers have examined patient and provider characteristics associated with the receipt of preventive services for diabetes. However, despite the high prevalence of comorbidities among people with diabetes, little is known about whether receipt of preventive services is associated with chronic comorbidities that require complex care. Methods: This study will analyze cross-sectional and longitudinal data from the 2000-2002 Medical Expenditure Panel Survey, a nationally representative survey of the U.S. civilian, noninstitutionalized population. The study population was over the age of 18, had diabetes, and completed a survey on disease treatment and severity. The dependent variables will be based on self-reported receipt of preventive services. The main independent variable will be the presence of medically complex conditions, which are chronic conditions that are prevalent in the population and that an expert panel identifies as requiring complex treatment. Control variables will include predisposing, enabling, and need characteristics. The first study hypothesis is that among persons with diabetes, chronic comorbidities that have a high level of medical complexity are associated with not receiving preventive services for diabetes mellitus, after adjusting for predisposing, enabling, and need characteristics. The second study hypothesis is that among persons with diabetes, chronic comorbidities that have a high level of medical complexity are associated with consistently low quality of preventive care over a 2-year period, after adjusting for predisposing, enabling, and need characteristics. Significance: This study will provide greater understanding of the challenges of providing high-quality care to persons with diabetes and medically complex comorbidities, thus addressing the Public Health Service's of Healthy People 2010 goals and the Agency for Healthcare Research and Quality's mission of improving quality of care, particularly for persons needing chronic health care. [unreadable] [unreadable] [unreadable] [unreadable]